The invention is directed to an arrangement for expelling highly volatile impurities from the ground water and the soil through which the latter flows. More particularly, it relates to an arrangement for expelling highly volatile impurities from the ground water and the soil through which the water flows by means of producing a vacuum in a well shaft which is driven into the area of the contaminated ground water and by means of directing a gas below the water level into the well shaft. Such an arrangement is already known from DE-PS No. 38 11 962. A vertical flow of ground water in the well shaft can be benefitted by means of this arrangement.